Hysteresis and Trap Emission in dc-Biased Integrated Lithium Niobate Electro-optic Modulators

The electro-optic (EO) effect is crucially important for low power and efficient tuning of integrated photonic circuits. However, in EO materials such as lithium niobate, dc biasing for an extended duration of time results in the emergence of numerous nonidealities, including hysteresis─a persistent degradation of the magnitude and linearity of the dc EO response. We show that EO hysteresis can be reversed under both zero-bias and reverse-bias conditions, given sufficient time or reverse voltage and consistent with a defect model of the underlying physics. Specifically, we infer that drift phenomena at short time scales may arise from charge trapping dynamics near the contact junction and thereby devise an active reset protocol that restores the magnitude of the response and partially restores the drift time scales.